U.S. Pat. No. 5,565,241 granted to Mathias et al on Oct. 15, 1996 entitled "Convergent End Effector", U.S. Pat. No. 5,307,992 granted to Hall et al on May 3, 1994 entitled "Method And System For Coating A Substrate With A Reinforced Resin Matrix" and U.S. Pat. No. 5,579,998 granted to Hall et al on Dec. 3, 1996 entitled "Method For Coating A Substrate With A Reinforced Resin Matrix" of which the inventor Jack G. Scarpa is a co-inventor and which these patents are commonly assigned. These references disclose a spray gun that utilizes a nozzle that is designed to configure the spray emitted by the nozzle into an atomized convergent plume of liquid resin and targets the plume with reinforced filler material immediately downstream of the nozzle to mix and wet the filler just prior to being applied to the surface of the substrate. In other words, the reinforcing material is entrained around the atomized liquid resin flow and is caused to be captured thereby, mix therewith and become an homogeneously wetted coating material that after impact with the substrates becomes cured into a substantially reasonably thick coating exhibiting good strength and resistance characteristics. The gaseous transport stream together with the eductor deliver the ingredients in the proper proportions and the air stream for causing the atomization and mixing to provide the proper amounts of material to assure that the coating is uniform and consistent. Heating is applied in the proper sequence to assure that the viscosity is at the proper level to assure evenness of flow.
As one skilled in this technology would appreciate, the heretofore known spray application equipment for spraying of highly loaded paints and coatings which require the addition of a high volume of solid large granular materials such as cork, glass micro spheres, granular or powdered materials in the 3 to 300 microns range require large amounts of solvents to dilute solid contents down to a level where it can be sprayed effectively. This, of necessity, requires special spray equipment designs that need to be significantly large in order to effectively spray these materials. Such systems have heretofore been designed to operate in a room or compartment that include a robot that was programmed to hold the spray gun and apply the spray. An additional room houses the supply of materials to be mixed and sprayed, the various valves, hoppers, proportioning devices and the like are separated from the spray gun room and a separate room housed the computer equipment and controls that served to control the various valves, proportioning devices etc, to automatically effectuate the spraying.
These special very large spray equipment designs leads to very low actual transfer efficiencies for spraying these coating materials. These low transfer efficiencies have a significant impact on the quantities of materials, solvents and volatile organic compounds that are released into the environment. As one skilled in this technology will appreciate, from an ecology standpoint these conditions are not preferred as is recognized by the Environmental protection Agency and Occupational Safety and Health Administrations that are tightening regulations that mandate change.
While the sized the gun of this invention retains all of the features of the heretofore known convergent spray gun utilizing the end-effector, this spray gun is capable of supplying the same amount of coating for each pass of these heretofore known spray guns. This spray gun is characterized as being portable and capable of being held by one hand in the same way that a commercially available paint spray gun is handled. In this mechanism concentric tube assembly is added to a modified commercially available spray nozzle, such as spray nozzles produced by Binks, Franklin Park, Ill and Grace, Detroit, Mich. that provides an inner tube that transports the resin and an outer tube that transports the air for atomizing the mixture and the dry powdered nozzle and its convergent cap. This arrangement of the concentric tubes allows the dry powdered nozzle that transports the dry powder material into a manifold to be propelled into the resin/air atomization plume. The dry granular materials and atomized resins become entrained at this point and thoroughly mix together outside the gun before being deposited on the substrate.
This patent application constitutes an improvement over the structure described in the U.S. Pat. Nos. 5,5645,241, supra 5,307,992, supra and 5,579,998. Essentially these patents are designed in a closed room environment where the spraying is done in a separate room from where the controls and ingredients are held and the spray gun is held by a robot so that the size and weight are not critical. As a matter of fact, the heretofore known designs of the convergent type of spray gun described above is much too heavy to be hand operated.
This invention is directed to a portable system where all of the controls, computers, valves, hoppers, eductors, proportioners and ingredients are contained in a portable cart and a hand-held spray gun is utilized with this system. Obviously, making the system portable increases the flexibility of the system and permits use of the system in different areas and locations. While the heretofore known systems include mechanism for purging the spray gun, this is not a particular concern where the system is in place and non-portable. Because of the portability of the system a more positive shut-off system was required to assure that the resin didn't remain in the gun and become hardened over a period of time when the spray gun was not in use. This invention provides a positive shut down system that shuts the system down when the spray gun is turned off. A back-up alarm system is utilized to warn the user that the gun has not been purged after a given period of time.